One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10,12,14)(11,13,15,16)(17,18)(19,23)(20,22)(21,24)(26,30)(27,33)(28,36)(38,40)(4,8)(6,7)(17,18)(19,23)(20,22)(21,24)(25,26,29,30)(27,34,33,31)(28,37,36,32)(35,38,39,40)(2,3)(6,7)(17,18,20,22)(19,21,24,23)(25,26)(27,31)(28,37)(29,30)(32,36)(33,34)(35,40)(38,39)(1,3,5,2)(4,7,8,6)(9,10)(11,13)(12,14)(15,16)(17,18)(19,21)(20,22)(23,24)(25,27,29,33)(26,31,30,34)(28,35,36,39)(32,38,37,40)(1,4)(2,6)(3,7)(5,8)(9,11,12,15)(10,13,14,16)(17,19,20,24)(18,21,22,23)(25,28)(26,32)(27,35)(29,36)(30,37)(31,38)(33,39)(34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.